Emergency release latch mechanism for smoke hatch



June 23, 1970 J LYQNS I 3,516,198

EMERGENCY RELEASE LATCH MECHANISM FOR SMOKE HATCH Filed Jan. 21, 1969 3 Sheets-Sheet 1 INVENTOR.

ROBERT J. LYO/VS BY W & ATTORNEYJ June 23, 1970 R. J. LYONS 3,516,198

EIERGENCY RELEASE LATCH MECHANISM FOR SMOKE HATCH Filad Jan. 21, 1969 3 Sheets-Sheet 3 INVENTOR. ROBERT J. L YONS June 23, 1970 R. J. LYONS 16,

' EMERGENCY RELEASE LATCH MECHANISM FOR SMOKE HATCH 3 Sheets-Sheet 5 Filed Jan. 21, 1959 ROBERI' J. LYONS 2; ATTORNEYS Patented June 23, 1970 Int. Cl. E051 /20 U.S. Cl. 49-1 8 Claims ABSTRACT OF THE DISCLOSURE An emergency release latch mechanism for a hinged cover of a hatchway construction, wherein the cover is heavily spring biased to open position but is normally restrained in closed position by the latch mechanism. The mechanism includes an emergency-actuated release member such as a low-temperature fusible metal link which, through a leverage for reducing the tensile load on the link to a low value, normally retains a latching dog in engagement with a shackle pin on the cover but assures positive disengagement therefrom to release the cover to open position in the event of actuation of the emergency-actuated release member.

This invention relates in general to an emergency release latch mechanism, and more particularly to latch mechanisms for roof-mounted smoke hatches for buildings.

Building smoke hatches are widely used for venting the inside of a building quickly to exhaust smoke or poisonous or explosive gas accumulation resulting from a fire in the building. As a rule, these hatches are not used as an entryway to a building except in emergency. For safety purposes the cover or covers of the hatch are hinged and are heavily spring loaded to open position in order to effect rapid opening in an emergency, not only against their own weight but also against natural restraining forces such as wind or accumulated snow or ice. Since the cover areas are fairly large, the spring loading on the covers must be substantial to overcome these restraining forces. In addition, there are transitory uplift forces caused by wind passing over the covers, so that total door-opening forces may range for example from several hundred to as much as 1000 pounds or more per door in typical installations. Such preloads on the door or cover are opposed in the closed condition of the hatch cover solely by the latch mechanism employed. The unit forces acting in the latching dog and shackle members are accordingly exceedingly high, making it a problem to provide an arrangement which is capable of securely latching the cover in closed condition, yet requires only a minimum force to effect release upon occurrence of a fire or explosion.

It is common practice in the prior art to effect automatic release of the latch and consequent opening of the hatch cover in case of fire emergency by employing devices incorporating a low melting point metal link which automatically ruptures upon attainment of a predetermined elevated ambient temperature as a result of a fire in the building. Attempt to employ fusible links directly connected to the hatch cover is unsatisfactory where, as indicated above, the preload forces on the cover are of such high order, since fusible links which have a sufficiently low melting or fusing temperature to be effective for fire detection purposes inherently lack the necessary tensile strength to continuously resist the heavy preload forces of the doors in closed position. Realizing such drawback, attempts have been made heretofore to provide an emergency release device which will withstand the high loading on the latch mechanism without adversely affecting the temperature at which it is set to release in case of a building fire. Such attempts include arrangements involving the mounting of a number of fusible links in tandem; but the difficulty then encountered is one of balancing the load equally among the several links and effecting simultaneous design failure of them at a predetermined ambient temperature. Other proposals for solving the problem have included fusible links mounted in a triangulation device providing leverage for the link in order to reduce the loading forces carried by the link. Although this type of arrangement affords improvement in that the loading on the link is reduced, such arrangements have still presented a number of deficiencies due to the relative mechanical complexity and consequent difiiculty of accurate adjustment and assured operation, and the amount of space needed to accommodate them. There have also been deficiencies in prior arrangements proposed for allowing the hatch door or doors to open in case of explosion within the building.

It is a principal objective of the present invention accordingly to provide an emergency release latch mechanism for heavily spring biased covers of smoke hatches and the like, which effectively reduces the unit forces acting on the emergency-actuated release element itself, e.g. a fusible link, yet is compact and mechanically simple and certain in operation. Another object is to provide a device of the character described which permits manual release of the latch without disrupting the fusible link element or other automatic emergency-actuated release member, so that upon reclosing the hatch cover and re-engagement of the latch mechanism, such emergency-actuated release member is again automatically effective. A further object in the design of the novel latch mechanism here disclosed is to provide a latch mechanism which may be readily operated in tandem with another mechanism of identical construction, both being under the control of a single emergency-actuated release element, where it is desired to employ two or more latch means on the same door or cover, or Where the hatch employs a double door each having at least one emergency release latch mechanism.

The invention is illustrated in the embodiment of a latch mechanism for double doored vent or smoke hatch construction shown in the accompanying drawings and described in further detail herein after. In the drawings:

FIG. 1 is an end elevational view of a double-doored smoke hatch incorporating the novel latching mechanism, the hatch being positioned on an access opening in the roof of a building, one end wall of the hatch being removed in the illustration to shown the interior construction more clearly;

FIG. 2 is an enlarged end elevational view of the latching portion of the construction shown in FIG. 1;

FIG. 3 is a view similar to that of FIG. 2 but with parts shown in actuated or released position of the latch;

FIG. 4 is a top plan view of the latch mechanism taken on line 4-4 of FIG. 5;

FIG. 5 is a side elevational view of the latch mechanism;

FIG. 6 is a semi-schematic illustration of a modified form of emergency-actuated release member in the latch system; and

FIG. 7 is a fragmentary view, partly in section, of another form of emergency-actuated release member for the latch system.

Referring to FIG. 1, a smoke hatch is shown in closing relation to an access opening A let into the roOf R of a building through which smoke or gases are to be relieved or vented. The hatchway includes the usual fixed structural members comprising interconnected side walls 12 and gabled end walls 14 (of which only the one is shown in FIG. 1). Side walls 12 are braced transversely of the hatch by angle member 16 extending centrally across access opening A in one direction, while end walls 18 are interconnected between their apices by a longitudinal channel 18. The side end walls are bolted or otherwise secured to the roof R in conventional manner around the access opening A.

Mutually closing covers 20 are each hinged along a top edge of a respective side wall 12, as at 22, and swing mutually inwardly and downwardly into closing position relative to the supporting hatch structure and access opening A. In the fully closed condition, the free edges of the covers substantially abut in the trough formed by longitudinal channel 18. The covers are spring biased to open position relative to the hatch structure by sets f compression spring members 24. These are mounted between and secured to the side walls and covers 20 in conventional manner. Depending on the size of the doors, a number of sets of compression members 24 will be employed on each door in order to give a total opening or lifting force sufficient not only to overcome the weight of the door but the additional weight of any loading imposed on it by wind forces or accumulated snow or ice. In order to cushion the sudden shock of the doors in arriving at full open position, as when the hinged edges of the doors swing back against stop members 26 fastened to the side walls 12 of the hatch structure, it is conventional to provide shock absorbers 28 which are also attached to and extend between the side walls 12 and covers 20 in known manner.

In order to retain the covers 20 in closed position, as shown in FIG. 1, against the opening force of compression spring members 24, each cover is provided with latching means at its free or unhinged edge. Such means comprise latch mechanism indicated generally at 30 suitably secured to fixed structural members of the hatch, and a cooperating shackle arrangement 32 mounted on the underside of the respective covers 20.

Since the latch means is identical for each of the two doors, only one such latch 30 and cooperating shackle 32 will be described herein, it being understood that the other is merely a duplication of the first.

Referring to FIGS. 2 and 3, the latch structure 30 comprises a longitudinally reciprocable bar 34 which is supported for sliding movement in a sleeve or bearing 36, the latter being welded or otherwise secured to a generally S-shaped structural brace 38 which extends from longitudinal channel member 18 downwardly to the vertical Web of the transverse angle member 16, being suitably secured to each of such members, again as by welding.

Reciprocable bar 34 has a clevis 40 secured to its upper end, and a latching dog 42 is pivotally mounted in the clevis by a pin 44 extending between the legs thereof. Dog 42 is roughly S-shaped and is pivotally supported by the clevis pin near its center for rocking motion in a vertical plane, whereby to move the upper hook portion 46 into and out of latching engagement with a generally horizontally extending shackle pin 33 carried by shackle member 32 on door 20. The hook portion 46 of the latching dog 42 is so designed that when fully engaged with shackle pin 33 in the closed position of door 20, dog 42 is in over-center condition relative to the center line drawn between its pivot pin 44 and shackle pin 33, whereby the upward or opening force exerted by door 20 on the latching dog tends to rotate about pin 44 in a clockwise direction, as viewed in FIGS. '2 and 3, thereby reinforcing engagement of the hook portion 46 and shackle pin 33. In the latched condition shown in FIG. 2, reciprocable bar 34 is held in its downwardly or retracted position relative to sleeve 36 by an arrangement which will presently be described, whereby door 20 is prevented from swinging upwardly toward open position.

Referring now to FIGS. 3, 4, and 5, the means for restraining reciprocable bar 34 in the aforesaid downwardly retracted position is effected in the following manner. At its lower end, bar 34 is formed with a bend or offset 35 (FIG. 5) constituting a sear. A bracket 50, of open U-shaped configuration and having a central portion 51 terminating in a transversely extending short leg 52, is pivotally supported from transverse structural member 16 by suitable trunnion means 54 so as to cause said leg 52 to overlie sear 35 of reciprocable bar 34 and prevent upward movement of the latter. Leg 52 and trunnion 54 constitute a short-fulcrurned trigger for bar 34.

As mentioned above, the foregoing latch construction is duplicated for the other door and central portion 51 of bracket 50 interconnects the two leg or trigger portions 52 of the respective latch mechanisms, whereby each of them can be released simultaneously by actuation of the bracket 50. To this end, a lever 56 is fixed to bracket 50 and extends upwardly with its free end 57 terminating adjacent the undersurface of longitudinal channel 18. Free end 57 is normally engaged by a catch 58 secured to the end of a second lever 60. The latter is pivotally supported adjacent catch 58 in suitable trunnion means 61, and a fusible metal link 62 is connected by pins 63, 65 between the opposite free end of the lever and a bracket 64 mounted to the undersurface of longitudinal channel 18. Link 62 is designed to rupture or fail under a given tensile load at a predetermined ambient temperature and consitutes an emergency-actuated release member setting the emergency release latch mechanism in operation.

As will be seen from the foregoing description, the opening force imposed on a cover 20 by the compression spring means 24 is resisted in the latched condition of latch mechanism by engagement of the short-fulcrumed trigger portion or leg 52 of bracket 50 overlying the sear of reciprocable bar 34, thus holding the latching dog 42 in positive engagement with shackle 32 of the door. The restraining force exerted by leg 52 of bracket on reciprocable bar 34 produces reaction in lever 56, causing the latter to tend to rotate in a counterclockwise direction, as seen in FIG. 5. But this is normally prevented by catch 58 in the unactuated position of lever 60. However, upon rupture of fusible link 62, lever swings down by gravity to the dotted line position shown in FIG. 5, thereby causing catch 58 to release the free end 57 of lever 56. Lever 56 then swings counterclockwise, as seen in FIG. 5, causing short leg 52 to pivot out of overlying relation to sear 35 of bar 34. The bar may then move outwardly of the access opening to its extended position as illustrated in FIG. 3. This in turn allows cover 20 to start swinging movement towards open position, in the course of which the arcuate movement of shackle pin 33 moves that pin laterally so that the bearing contact of hook 46 with pin 33 is no longer in over-center position relative to pivot 44. When this condition is reached, latching dog 42 will rotate counterclockwise, as seen in FIG. 3, to effect disengagement of the hook portion 46 and shackle pin 33. As soon as such disengagement is effected, door 20 will of course be free to swing to its fully open position under the urging of compression spring members 24.

In order to provide a more positive and assured disengagement of hook portion 46 and shackle pin 33, latching dog 42 is formed with an arm 47 extending generally oppositely of hook portion 46. As latching dog 42 moves upwardly upon release of reciprocable bar 34, arm 47 of the dog strikes the horizontally projecting upper leg 39 of brace 38 so that continued upward movement of the dog causes positive counterclockwise pivotal movement about pin 44 on bar 34, thus positively effecting the release of the shackle pin.

In order to provide manual release of the latch, a cable 66 is connected to latching dog 42, and arm 47 provides a convenient point of attachment so that when the cable 66 is pulled vertically downward, dog 42 is pivoted out of latching engagement, without any vertical reciprocation of bar 34, releasing the door to swing open without disturbing the emergency release system under the control of the fusible link 62. If it is then desired to reclose the door, this can be accomplished by forcing it downwardly against the spring loading forces until shackle pin 33 again engages hook portion 46 of the latch. In order to facilitate this, hook portion 46 is suitably contoured on its upper end to provide a camming surface which, upon engagement by shackle pin 33, temporarily causes dog 44 to pivot counterclockwise until the pin 33 passes under the lip of the hook. In order then to assure positive re-engagement of the hook, a torsion spring 67 is provided on clevis 40 which bears against arm 47 of dog 42, biasing it in clockwise or shackle-pinengaging position. To prevent overtravel in that direction when the dog is not in engagement with shackle pin 33, the lower leg 43 of dog 42 is formed to provide a stop which abuts the upper end of reciprocable rod 34 within the legs of clevis 40.

Where, as illustrated in the accompanying drawings, a double-doored hatch and double latch mechanism is employed, the manual release effected by cable 66 can be paralleled by suitable yoke means 68 and a single cable 70 run from the yoke to any desired location using suitable sheaves, such as that indicated at 72 in FIG. 5, for guiding the cable around corners and the like.

In place of a fusible metal link, such as link 62, other 5 emergency-actuated release means can be employed, as for example a solenoid-operated latching bolt which normally restrains the free end of lever 60. Such an arrange. ment is shown in FIG. 6 wherein solenoid 74 is provided with an armature pin 76 normally engaging the free end of lever 60. Solenoid 74 is energized to withdraw armature pin 76 under the control of some suitable sensor de-- vice 78 such as a photoelectric cell, capacitance-operated switch, or bimetallic heat-operated switch for example, of standard known construction located in an appropriate 5 position in the building to be protected thereby. The sensor device 78 may also be adapted for operation by pressure, rather than temperature, where it is desired to cause the hatch doors to open in case of an explosion occurring in the building. It will be apparent too that sensor devices of both types, i.e. heat and pressure, may be employed together in an installation by paralleling the devices in the control circuit of solenoid 74.

A further form of emergency-actuated release means is shown in FIG. 7 which is particularly designed fort opening the hatch in case of an explosion. The arrangement comprises a panel 80 of predetermined area which is made fast to a leg 82 of a bell crank 84 whose short leg 86 is pivotally mounted on channel 18. Panel 80 is sup ported in the hatch opening, below a door 20, so as to be responsive to outward pressure of an explosion occurring in the building. To this end, an L-shaped pin 88, having a shoulder 90, is used in bracket 64 to replace pin 65 as seen in FIGS. 4 and 5, with the short leg of the L engaged in an elongated slot 92 of hell crank 84. Shoulder 90 abuts an arm of bracket 64 in the normal condition of the device and thus supports panel 80 in the position shown in solid lines in FIG. 7. Upon the occurrence of an explosion in the building, the sudden upward (outward) pressure acting on panel 80 causes it to pivot upward, thereby withdrawing pin 88 from bracket 64, allowing link 62 and its associated arm to fall free and actuate the latch mechanism, as already described.

What is claimed is:

1. An emergency release latch mechanism for a hinged cover of a hatchway, wherein the cover is heavily spring biased to open position but is normally restrained in closed position by said latch mechanism and wherein the said hatchway includes fixed structural members for supporting said cover and for mounting it on an access opening to be served thereby, said emergency release latch mechanism comprising in combination:

a longitudinally reciprocable bar, and bearing means supporting said bar on a fixed structural member adjacent the underside of said cover at the unhinged 75 edge thereof and permitting reciprocation of said bar between extended and retracted positions respectively outwardly and inwardly in relation to the access opening;

a latching dog pivotally secured to the outer end of said bar and disposed normally thereby adjacent the underside of said cover, said dog having a hook portion at its free end and being swingable about an axis generally parallel to the plane of said access opening and means urging said latching dog in a predetermined latching direction;

a shackle pin secured to the underside of said cover in position for engagement by said hook portion of said latch dog when said cover is closed to maintain said cover closed against its spring bias;

an offset portion on said reciprocable bar constituting a sear, and lever means pivotally supported on a fixed structural member closely adjacent said offset and having a short-fulcmmed trigger portion engageable with said sear in normal closed position of said cover and latch dog to prevent outward movement of said reciprocable bar and latchin dog;

and means connecting the remote end of said lever means to a fixed structural member through an emergency-actuated release member; said last named release member when actuated allowing said lever means to pivot in a direction causing disengagement of said sear and trigger portions of the latch mechanism, whereby said reciprocable bar and latching dog are free to move towards extended position under the urging of the spring bias on said cover to permit withdrawal and disengagement of said shackle pin from said hook portion of said dog as said door swings open.

2. An emergency release latch mechanism as defined in claim 1, wherein said latching dog has an arm portion extending generally oppositely of said hook portion, and said latch mechanism includes a fixed abutment member disposed for engagement by said arm portion of said latching dog as the latter is moved to its extended position to cause positive pivotal movement and disengagement of said hook portion from said shackle pin, said fixed abutment being spaced from said arm portion of said dog in the retracted position of the latter.

3. An emergency release latch mechanism as defined in claim 1 for use in a hatchway construction having a pair of hinged covers, wherein said latch mechanism includes duplicate sets of said reciprocable bar and pivotable latching dog, one such set being disposed adjacent the underside of each cover at an unhinged edge thereof;

0 and shackle pins on each of said covers disposed for engagement by the respective latching dogs; said lever means having dual short-fulcrumed trigger portions engageable with the respective offset sear portions of said reciprocable bars in the retracted positions of said latch- 5 ing dogs whereby to effect simultaneous release to extended position of said latching dogs on pivotal movement of said lever means when released by said emergency-actuated release member.

4. An emergency release latch mechanism as defined in claim 1, wherein said emergency-actuated release member comprises a low-temperature fusible metal link.

5. An emergency release latch mechanism as defined in claim 1, wherein said emergency-actuated release member comprises a remotely controlled solenoid operated latching pin.

6. An emergency release latch mechanism as defined in claim 1, which further includes cable means connected to said latching dog to effect pivoting thereof manually from a remote position and release of said shackle pin 0 by said dog.

7. An emergency release latch mechanism as defined in claim 1, wherein said lever means comprises first and second interconnected levers, said first lever engaging said sear of said reciprocable bar and said second lever being pivotally supported adjacent the remote end of said first 7 lever and having a short-fulcrumed trigger portion engageable therewith but disengageable therefrom on pivotal movement of said second lever from a normal position, said emergency-actuated release member being connected to the remote end of said second lever to releaseably restrain it in said normal position.

8. An emergency release latch mechanism as defined in claim 1, wherein said emergency-actuated release member comprises an explosion-operated panel, said panel being pivotally supported on a fixed structural member in said hatchway, said panel having means engaging said remote end of said lever means and normally restraining said lever means but disengageable therefrom on explosive impact striking said panel causing it to pivot and free said panel means from restraining engagement with said lever means.

References Cited UNITED STATES PATENTS FOREIGN PATENTS Canada.

DENNIS L. TAYLOR, Primary Examiner U.S. Cl. X.R. 

